Flight Related Studies

1. Flight Related Studies 141

2. Flight Related Studies Charges # 2,6 • Design of a thermal assembly • Experimental system and properties 142

3. Charges # 2,6 V 3D Upward Directional Solidification Setup Axial Camera Hot Block Radial Camera Cold Block 142a

4. Charges # 2,6 Liquid Liquid Solid Solid Pure SCN growth SCN-0.0026 wt.% Eth growth Interface Distortion Schaefer and Coriell, Metall. Trans., 15A(1984)2109 143

5. Charges # 2,6 Th=95.0oC, Tc=12.0oC Temperature Profiles: Effect of Th Th=75.0oC, Tc=12.0oC 144

6. Charges # 2,6 Axial View SCN-Ace. without Booster Heater Planar Interface Propagation Front Cellular Interface Billia et al. (2003) 144a

7. Charges # 2,6 g 500 mm Growth of SCN-salol without a Booster Heater 145

8. Numerical Model Charges # 2,3,6 V Axial Camera Hot Block Radial Camera Booster Heater Cold Block 146

9. Charges # 2,6 Th=75.0oC, Tc=12.0oC, Booster Heater off Th=75.0oC, Tc=12.0oC, Booster Heater T=54.0oC Temperature Profile: Effect of Booster Heater 147

10. Charges # 2,6 Axial View of SCN-water with Booster Heater on 147a

11. Charges # 2,6 3rd Layer g 2nd Layer 1st Layer 200 mm Growth of SCN-salol with a Booster Heater 148

12. Experimental System Selection 149

13. Charges # 2,6 Selection of the Experimental System Three different alloy systems were examined experimentally: • SCN – acetone • Acetone readily forms bubbles and is not desirable since • bubble formation can lead to fluid flow in a low gravity • environment. • SCN - salol • As the solute layer of salol builds-up, the solution loses its • clarity when viewed from the liquid side. • SCN – water • Water did not show any problems, and is desirable since • it is the major impurity in SCN. 150

14. Charges # 2,6 Properties of Pure SCN 151

15. Charges # 2,6 Properties of SCN-water (Acetone or Salol) 152

16. Charge # 2 Safety Considerations • Succinonitrile has been used in several flight experiments, • including the IDGE, MOMO and PFM experiments. NASA • has reviewed the safety of SCN and approved its use for other • flight experiments. No safety problem 153

17. Charges # 2,6 SCN - Water Phase diagram and required physical parameters 154

18. Charges # 2,6 Phase Diagram of SCN-Water (Smith, Frazier and Kaukler, Scripta Metall.) 155

19. Charges # 2,6 Validation of Liquidus Line The liquidus temperature was obtained by measuring steady-state cell tip temperature (Tt) and using the relationship: TL = Tt + GD/V. 156

20. Charges # 2,6 Estimate of Solute Partitioning Coefficient Two experimental parameters were measured: Critical velocity for planar interface instability was measured, which is given by Vc = GD/DT0, where DT0 is the freezing range for linear liquidus and solidus lines. Measurements of dendrite tip radius with velocity. VR2 = D/kT0* =Const. Combining the above results: k = (/*) (V/G)c /(VR2 ) k was estimated to be 0.03. 157

21. Charges # 2,6 Properties of SCN-Water • Diffusion Coefficient (Wan and Hunt, Acta Mater.) • Interface Energy and its Anisotropy (Glicksman et al.) • Refractive Index (DSIP study) • Density (Ecker, Frazier and Alexander, Metall. Trans.) 158

22. Charges # 2,6 Variation with composition Refractive Index of SCN-Water Variation with temperature 159

23. Charges # 2,6 Refractive Index of SCN-Salol

24. Charges # 2,6 Refractive Index of Pure Materials 160

25. Charges # 2,6 Refractive Index of Alloys 161

26. Property SCN liquid Charges # 2,6 Density (kg/m3) 984. Thermal conductivity k (W/m-K) 0.223 Heat capacity Cp (J/kg-K) 2000. Thermal expansion coeff. (K-1) 1.07x10-3 Solutal expansion coeff. (wt%)-1 2.06x10-4 Density of SCN-water Kinematic viscosity (m2/s) 2.6x10-6 162

27. Charges # 2,6 Experimental Observations and Measurements • Microstructure map for cellular and dendritic • microstructures as a function of V, G and C. This study • in thin samples was done to establish experimental • conditions for experiments on ISS. • Time required for the initial instability of a planar • interface. This is crucial in determining the length of • the run and the frequency of image capturing. • Measurements of primary cellular/dendritic spacing, • and cell/dendrite tip radius as a function of V, G and • C. The focus of this study is to obtain critical length • scales that will be measured from the experiments on • ISS. This range of length scales is required to establish • optical resolution required. 163

28. Charges # 2,6 V/G 103, mm2S-1 K-1 Microstructure Map (SCN-Water) • Regimes of stable cellular and dendritic microstructure. • (b) Cellular, dendritic and mixed microstructures as a function of V/G and composition. 164

29. Charges # 2,6 Time for Initial Planar Interface Instability SCN-0.5 wt % water. The longest time, at V=1.0 mm/s, is about three hours. 165

30. Charges # 2,6 Cell and Dendrite Regimes vs. V, G, C 166

31. Charges # 2,6 Velocity, mm/s Time and Distance to Reach Steady-state 167

32. Charges # 2,6 Dendrite Spacing 168

33. Charges # 2,6 Cell and Dendrite Spacing Variation with Velocity 169

34. Charges # 2,6 Dendrite Tip Radius 170

35. Charges # 2,6 Central Composite Design 171

36. Charges # 2,6,7 Matrix for Cells - Central Composite Design 172

37. Experimental Matrix for Reliable Analysis 173

38. Charges # 2,6,7 Experimental Matrix for Cellular Microstructures 174

39. Charges # 2,6,7 Experimental Matrix for Dendritic Microstructures 175

40. Charges # 2,6 Expected Microstructural Scales (Cont.) Cellular Spacing 177

41. Charges # 2,6 Expected Microstructural Scales (Cont.) Primary Dendrite Spacing 178

42. Charges # 2,6 Expected Microstructural Scales (Cont.) Dendrite Tip Radius 179

43. Charges # 2,6 Expected Microstructural Scales (Cont.) Primary Dendrite Spacing 180

44. Outline of Presentation • Introduction • Background • Ground-Based Research • Ground-Based Results, Experimental Plans and Objectives • Justification for Conducting Experiments in Space • Flight Experiment Plan • Flight Experiment Requirements • Principal Investigator’s Requirements • Hardware: DECLIC with Directional Solidification Insert 181

45. Charges # 1, 2, 3, 6 Ground-Based Results, Experimental Plans and Objectives • Theoretical objectives of the proposed ISS research • Brief Summary of Relevant Results From Ground-Based Research • Experimental Flight and Ground-Based Measurements • ISS studies • Ground-based studies and modeling 182

46. Outline of Presentation • Introduction • Background • Ground-Based Research • Ground-Based Results, Experimental Plans and Objectives • Justification for Conducting Experiments in Space • Flight Experiment Plan • Flight Experiment Requirements • Principal Investigator’s Requirements • Hardware: DECLIC with Directional Solidification Insert 183

47. Charges # 2,4,6 Justification for Conducting Experiments in Space • Limitations of Ground-Based Experiments • The Effect of Convection on Interface Pattern Evolution • Numerical Simulation of Convection • Eliminating Convection During Terrestrial Directional • Solidification: Experiments in Thin Samples 184

48. Charges # 2,4,6 Convection Effects 185

49. Charges # 2,4,6 Instability at the Center SCN-acetone SCN-salol 186

50. Charges # 2,4 Motion of a Particle in the Liquid Sample diameter 1 cm 187